Tetra(-dPEG®₁₁-DBCO)pentaerythritol

Tetra(-dPEG®11-DBCO)pentaerythritol, product number 11371, is a four-armed, discrete polyethylene glycol (dPEG®) crosslinker built around a pentaerythritol core. Each arm terminates with a dibenzocyclooctyne (DBCO) functional group. Each arm conjugates to an azide-functionalized molecule or surface via strain-promoted azide-alkyne cycloaddition (SPAAC). This product is useful for supramolecular construction (e.g., dendrimers) and for efficiently crosslinking azide-functionalized proteins or peptides.

PEGylation and "the dPEG® Difference"
This compound showcases the advantages of dPEG® products. Conventional polyethylene glycol (PEG) products are dispersed polymers. These polymers consist of a complex mixture of different chain lengths and molecular weights that make exact analysis and characterization quite challenging.

OurdPEG® products contain precisely defined, single molecular weight, discrete-length PEG chains (i.e., they are monodispersed PEG products). Tetra(‑dPEG®11-DBCO)pentaerythritol would be challenging to characterize if made with conventional PEG reagents because of polymer dispersity. The synthesis of a product like Tetra(‑dPEG®11-DBCO)pentaerythritol using standard PEG reagents creates a complicated assortment of different products. However, using dPEG® reagents, this product can be synthesized and characterized accurately. The clear advantage of dPEG® products is what we at Quanta BioDesign call "the dPEG® difference."

The DBCO functional group at the end of each dPEG® chain consists of a strained cyclooctyne ring with benzyl rings fused on each side of the cyclooctyne. A glutaric acid group extends from the nitrogen atom on the cyclooctyne ring to permit conjugation to a primary amine. DBCO is a bioorthogonal, copper-free click chemistry reagent that reacts with azide groups through strain on the cyclooctyne ring, hence the acronym SPAAC. The strain-promoted click reaction produces a triazole ring fused to the eight-sided ring, with corresponding changes in bond hybridization. SPAAC is useful for reactions where Cu(I) cannot be used due to toxicity issues (for example, with living cells) or for reactions where copper would be difficult to remove in the workup of the product.

Application References:

Hermanson, G. T. Chapter 18, PEGylation and Synthetic Polymer Modification. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, pp 787-838. Want to read a review of Greg's book?
Hermanson, G. T. Chapter 17, Chemoselective Ligation; Bioorthogonal Reagents. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, pp 757-786, particularly pages 769-775 where click chemistry is discussed.
Hermanson, G. T. Chapter 8, Dendrimers and Dendrons. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, 351-386.
Baskin, J. M.; Bertozzi, C. R. Bioorthogonal Click Chemistry: Covalent Labeling in Living Systems. QSAR & Combinatorial Science 2007, 26(11–12), 1211–1219. https://doi.org/10.1002/qsar.200740086.
Dommerholt, J.; Rutjes, F. P. J. T.; van Delft, F. L. Strain-Promoted 1,3-Dipolar Cycloaddition of Cycloalkynes and Organic Azides. Top. Curr. Chem. (Z) 2016, 374(2), 16. https://doi.org/10.1007/s41061-016-0016-4.

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